Conventional shear mode transmission clutches using magnetorheological fluids (MRFs) can be either disc-shaped or cylindrical. The major drawbacks of these devices include the effect of centrifuging at high rotational speeds and the subsequent sealing problems associated with it. This study develops models aimed at describing centrifuging and mitigates this issue by developing a MR clutch design where the fluid is encapsulated in a highly absorbent polyurethane foam.
High bandwidth actuation systems that are capable of simultaneously producing relatively large forces and displacements are required for use in automobiles and other industrial applications. Conventional hydraulic actuation mechanisms used in automotive brakes and clutches are complex, inefficient and have poor control robustness. These lead to reduced fuel economy, controllability issues and other disadvantages. Recently, a two-stage hybrid actuation mechanism was proposed by combining classical electromechanical actuators like DC motors and advanced smart material devices like piezoelectric actuators. This article discusses the development and implementation of a model predictive control methodology for controlling this two-stage actuation system in tracking various reference inputs. Additionally, this methodology also employs a unit-step delayed disturbance estimate to account for actuator hysteresis, other nonlinearities and unmodeled dynamics in the system. Finally, the article highlights the effectiveness of this control methodology experimentally by tracking various reference inputs.
Magnetorheological (MR) dampers are easily controlled by appropriately regulating the current through an electromagnet producing the necessary magnetic field across the fluid; thus they can be utilized in applying advanced nonlinear control strategies aimed at vibration suppression problems. Since most MR dampers are passive (i.e., they are dissipative and do not produce motion) modern nonlinear control schemes must be significantly modified before they can be employed. This study presents the theoretical development of a modified nonlinear control methodology for MR dampers applied to typical vibration control problems. The methodology is applied to single and multiple DOF systems. The case when only one measurement sensor is used in a quarter-car model is also analyzed using a classical observer design. Simulated and experimental results show the effectiveness of the methodology in controlling the vibration of a general vibratory system.
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